Hi Robert,
A b-mercaptoethanol molecule probably reacted with your cysteine to form
a mixed disulfide. In this case the ethanol part would be disordered.
Herman
________________________________
From: CCP4 bulletin board [mailto:[email protected]] On
Behalf Of Cheng, Robert
Sent: Thursday, July 09, 2009 11:05 AM
To: [email protected]
Subject: [ccp4bb] modified cysteine
Hi all
I am refining this structure and encountered this extra blob of
density on a cysteine residue. It looks like the cysteine has been
modified in some way. The density seems very strong (remain visible at
5sigma fofc). I wonder if someone could tell me what modification has
taken place. The density would fit a MET residue perfectly but DNA
sequence confirms it is a cys. The buffer contains b-mercaptoethanol,
PEG, MgAcetate, Tris, Hepes, NaCl and glycerol.
Many thanks for your help.
Robert
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